PATENT ABSTRACTS 369

BRADYRHIZOBIUM JAPONICUM MUTANTS EXHIBITING

SUPERIOR SOYBEAN NODULATION

Robert M Zablotowicz, Robert G Upchurch, James Ligon, Toronto, NC, Canada assigned to Lipha Chemicals Inc

Mutant strains of Bradyrhizobium japonicum having enhanced nodulation properties were created by transposon mutagenesis of known Bradyrhizobium japonicum strain I-l 10. The mutant strains grow well in a yeast-extract man- nitol medium, produce extracellular poly- saccharides at a level greater than the parent strain under appropriate conditions, are capable of growth on a nutirent medium containing a normally inhibitory amount of succinic acid, and contain a 21 Kdalton protein absent from the parent strain. Such strains can be used to inocu- late soil in which soybean plants are grown, resulting in improved plant yields.

4865967

AUTORADIOGRAPHIC GENE SCREENING METHOD

Hisashi Shiraishi, Junji Miyahara, Hisatoyo Kato, Minami Ashigara, Japan assigned to Fuji Photo Film Co Ltd

An autoradiographic gene-screening method employing a hybridization process, which com- prises: (I) a step of transferring a portion of genetic clones cultured on a culture medium onto a filter to fix them thereonto; (2) a step of hybridizing the genes of said clones fixed onto said filter with radioactively labeled probes; (3) a step of obtaining two dimensional information on the location of the radioactively labeled sub- stances on the filter which comprises placing said filter having been subjected to the hybridization and a stimulable phosphor sheet in layers for a given period of time to cause said stimulable phosphor sheet to absorb at least a portion of radiation energy emitted by the radioactively labeled substances on the filter, exciting said sheet with an electromagnetic wave to release the radiation energy stored in said sheet as stimulated emission, and detecting the stimulated emission to obtain a locational in- formation on the radioactively labeled sub- stances on the filter; and (4) a step recovering the

clones on the culture medium according to the obtained locational information.

4865968

DNA SEQUENCING

Leslie E Orgel, James W Patrick assigned to The Salk Institute for Biological Studies

A first mixture is prepared that contains labeled chain fragments which each has a common end adjacent to a primary nucleotide and a termina- tion at a position from the primary through an nth nucleotide, the first mixture containing nucleotide chain fragmentrof each length from termination at the primary through termination of the nth nucleotide. A second mixture is pre- pared that contains labeled chain fragments beginning at the common end and terminating at positions from the first through the nth nucleotide, the second mixture containing chain fragments of each length terminating wherever either a first or a second of the four nucleotides occurs. A third mixture is prepared that contains labeled chain fragments beginning at the com- mon end and terminating at a position from the first through the nth nucleotide, the third mix- ture containing chain fragments of each length terminating wherever the first or a third of the four nucleotide sequences occurs. The chains are electrophoresed with the first mixture as the cen- ter lane. This three-lane system provides a uni- que band pattern for each of the four nucleotides and permits the sequence to lx read merely by directly comparing each of the flanking lanes with the fully stepped center lane. This system has important advantages in reducing reading errors, particularly when read with computer- assisted scanning apparatus.

4865974

BACTERIAL METHIONINE N-TERMINAL PEPTIDASE

Arie Ben-Bassat, Keith A Bauer, Shing Chang, Sheng-Yun Chang assigned to Getus Corpora- tion

Methods for obtaining N-terminal methionine- free proteins involve a novel E. coli methionine amino pcptidase. The method is capable of in vitro or in vivo application. For in vivo applica- tion, a plasmid-borne DNA encoding the pep- tide is expressed in a bacterial host.